Glacial Landforms
In
Northern Minnesota
ECS Silviculture Class, Session 2
October 10, 2012
Direction of ice Flow
Minnesota’s Highs and Lows
BedrockIceGeology
Direction
Early to Mid-Wisconsinan (20,000 – 30,000 BP?)
-Ice advances from the NE
Late Wisconsinan (15,000 – 20,000 BP?)
- Warming climate results in retreat of glaciers
Wadena Lobe
“Later” Wisconsinan
- Outwash fans are deposited
over stagnant ice
Itasca Moraine
Mid-Wisconsinan – Ice cover
VERY Late Wisconsinan Advance of the St. Louis Sublobe from the
NW across most of Minnesota
Schematic from H. Mooers, UMD
Glacial Lake Agassiz
-Extensive clay-rich lake sediments
- Beach ridges
Holocene (post-glacial) Aeolian Deposits
-Sand Dunes
-Widespread silt caps (loess)
Grand Rapids
Duluth
Post-Glacial Landform Development
in Present-day Northern Canada
Glacial Landforms
Terminology and Descriptions
• Ice-related Landforms:
– Supra-glacial
– Sub-glacial
– Pro-glacial
• Post-glacial Landforms:
– Fluvial (river sediments)
– Aeolian (dunes, loess)
Glacial landform influences
on vegetation
- Texture
- Hydrology
- Lithology (chemical makeup of
sediments)